1. Field of the Disclosure
The invention relates to fluid processing systems and methods. More particularly, the invention relates to systems and methods for detecting air in a fluid return line and automatically purging the air therefrom.
2. Description of Related Art
Various blood processing systems now make it possible to collect particular blood constituents, instead of whole blood, from a blood source such as, but not limited to, a container of previously collected blood or other living or non-living source. Typically, in such systems, whole blood is drawn from a blood source, a particular blood component or constituent is separated, removed, and collected, and the remaining blood constituents are returned to the blood source. Removing only particular constituents is advantageous when the blood source is a human donor, because potentially less time is needed for the donor's body to return to pre-donation levels, and donations can be made at more frequent intervals than when whole blood is collected. This increases the overall supply of blood constituents, such as plasma and platelets, made available for transfer and/or therapeutic treatment.
Whole blood is typically separated into its constituents (e.g., red cells, platelets, and plasma) through centrifugation, such as in the AMICUS® separator from Fenwal, Inc. of Lake Zurich, Ill., or other centrifugal separation devices, or a spinning membrane-type separator, such as the AUTOPHERESIS-C® and AURORA® devices from Fenwal, Inc.
In some of these systems, an air detector is provided for detecting the presence of air bubbles in fluid being returned to the blood source. Known systems typically include an alert and/or alarm system that is programmed to generate an alert and/or alarm when air is detected in a fluid return line, which causes the pumps of the system to stop operating and closes the clamps or valves of the system to prevent air from being injected into the blood source. The intervention of an operator is then required to remove the air from the fluid return line, such as by pressing a button to cause the air to be vented from the fluid return line and then pressing another button to restart the system after visually confirming that the air has been vented. However, human interaction may prolong the time that the system is paused or inoperative, especially if a single operator is overseeing the simultaneous operation of multiple systems. Accordingly, the need remains for a fluid processing system that can automatically purge air from a fluid return line without requiring human intervention.